Reference Ranges for Placental Perfusion Using Magnetic Resonance Imaging (MRI)PLACENTIMAGE

To evaluate the feasibility of functional MRI method developed in an animal model and to construct normal reference ranges for in vivo placental perfusion using functional MRI. This will be based on imaging studies in patients undergoing termination of pregnancy (TOP) at 16 to 32 weeks' for fetal reason in a tertiary referral center.

Objective: To evaluate the feasibility of functional MRI method developed in an animal model and to construct normal reference ranges for in vivo placental perfusion using functional MRI. This will be based on imaging studies in patients undergoing termination of pregnancy (TOP) at 16 to 32 weeks' for fetal reason in a tertiary referral center. Method: All patients undergoing TOP at 16 to 32 weeks will be offered to participate in this study. 120 patients will be included. 15 per group of weeks of gestation: 16+0-17+6 SA, 18+0-19+6 SA, 20+0-21+6 SA, 22+0-23+6 SA, 24+0-25+6 SA, 26+0-27+6 SA, 28+0-29+6 SA, 30+0-31+6 WG. MRI will be performed in the same hospital, during hospital stay, within 45 minutes. Two MRI sequences will be used to measure placental perfusion: * dynamic sequences using Gd contrast agent. * " spin tagging ", which do not need any contrast agent. Perfusion will be modelled using compartmental analysis. Reference ranges will be build up by statistical modelling. Gadolinium assays will be performed on amniotic fluid and placental tissue following TOP. Duration of inclusion: 24 months. Duration of patient participation: 45 minutes. Expected results: * Feasibility in routine practice. * Reference ranges for placental perfusion. * Comparison between the two measurements methods. Adverse outcome measure: Nausea, vomiting, lack of comfort and other adverse outcome.